1900s: Disease Eradication

1980s: Paradigm Shift

2000: Measles Elimination

2014: Disneyland Outbreak

2015: California SB 277

2015: Current Climate

The measles elimination success story was short lived in the United States. Between 2001-2008, 557 cases resulted from 38 outbreaks. A significant finding was identified. Of the 557 cases, a total of 232 cases (43%) resulted from imported measles viruses of 44 countries across the world. This signified that foreign outbreaks of measles posed a threat to the American population. The measles genotypes that were identified during this time period were D3-D9, H1, H2, and B3, and they originated from Asian, African, and European countries. An average of nine cases resulted from each outbreak and they lasted between 3 to 79 days. These short-lived outbreaks affected infants 6-11 months and children 12-15 months the greatest, which increased the epidemiological count of “years of potential life lost” and “disability-adjusted years”. This outcome resulted from the lack of child immunization due to medical, religious, or personal exemptions and lower immunity from only receiving the first dose of the MMR vaccine. 73% of case-patients in 2001 and 95% of case-patients in 2008 were unvaccinated or had an unknown vaccination status. In addition, between 2001 and 2008, 91%-93% of 19-35 month old children had the first measles vaccination dose, but only 87% to 89% of adolescents between 2006 and 2008 had the second dose (1). In 2011, the United States experienced an even larger outbreak with the highest number of cases since 1996. During this year alone, there were 211 confirmed cases and 15 outbreaks of measles across the nation (4). It did not stop there.

From Elimination to Deadly Outbreaks: What Went Wrong?

Various factors contributed to the rise of measles cases between 2001 and 2014. A study regarding vaccine refusal demonstrated that the lowest rates of vaccination were among wealthy, well-educated communities with excellent health insurance. This outcome demonstrates that the lack of immunization was not a result of low vaccine accessibility, but instead was rooted in shifting sociocultural perspectives of the measles vaccine during the 1980s. Parents did not feel urged to vaccinate their children and filed vaccine exemptions because the elimination of measles in 2000 rendered the presence and potential dangers of the measles vaccine invisible. In addition, many people chose to not vaccinate their children due to safety concerns. Multiple studies during this time noted that 2-10% of immunized patients who received two doses of the measles vaccine experienced secondary vaccine infection due to their body’s failure to develop sufficient protective antibodies. Other studies demonstrated associations between the measles vaccine and autism, which ignited a strong anti-vaccine movement (4). These motivations lowered rates of population immunity and protection from herd immunity after 2000. This, in combination with increased exposure to the measles virus through infected international visitors and immigrants, caused a large number of individuals to suffer from measles outbreaks in the 21st century.

Impact of foreign virus carriers on disease prevalence in the United States (2):

2011: France experienced the largest measles outbreak among 30 countries in the World Health Organization’s European Region. Most of the cases that were reported in the United States were from France. For more information see Measles — United States, January-May 20, 2011.

2014: A large outbreak occurred within the unvaccinated Amish communities in Ohio. Many of the cases found during this year were associated with measles cases that arose from the Philippines outbreak. For more information see the Measles in the Philippines Travelers’ Health Notice.

Although California is known to have generally high vaccination rates for MMR, it’s believed that pockets of unvaccinated individuals perpetuate the spread of measles in niche communities during outbreaks.

Big headlines hit news reports when a strong measles outbreak arose in Anaheim, California within the Disneyland Theme Park in December 2014. It was suspected that a foreign traveler visited the amusement park while sick with the virus, which lead to rapid transmission of the disease. CDC officials were notified of an existing case and immediately established surveillance and treatment systems for those who were infected. From January 1 to May 1, 2015, the CDC reported a total of 169 cases from 20 different states [AZ, CA, CO, DC, DE, FL, GA, IL, MA, MI, MN, NE, NJ, NY, NV, OK, PA, SD, TX, UT, WA] and the District of Columbia (2).

Since California was the site where the outbreak originated, it was the area in which most cases were found. Out of the 169 people infected, 110 of them were California residents who ranged from 6 weeks to 70 years of age. Forty-nine patients overall, making up 45% of the entire infected population, were unvaccinated. 12 of those unvaccinated cases were infants who were too young (<12 months) to be vaccinated. Twenty-eight of those who were also unvaccinated (18 children and 10 adults) had intentionally not received the vaccine due to personal beliefs. Five of the people who were infected had only one dose of the measles vaccine, and 7 people had two doses. Forty-seven percent of all patients had unknown vaccination statuses (3). The rapid spread of this news via social media, newspapers, cell phones, and word of mouth ignited a wide public concern over this detrimental disease.

“Measles Cases and Outbreaks.” Centers for Disease Control and Prevention. Centers for Disease Control and Prevention, 27 Apr. 2015. Web. 16 May 2015. <http://www.cdc.gov/measles/cases-outbreaks.html>.